as Infusoria flagellata, 213 



the general appearance of this part of the organism, it may be 

 added that the older and basal portions (fig. 63) of the branches 

 are flat, and have a distinct longitudinal irregular striation, 

 to all appearance made up of the older, laterally agglutinated 

 twigs. The youngest, terminal portions (fig. Al^pd) of the 

 branches which, under the name of twigs, have been described 

 in this paper as the immediate supporters of the colonies of 

 monads, are evidently tubular (fig. 62). They appear to be 

 as flexible as a spider's thread, and are usually quite irregular 

 in outline, and in the calibre of the canal which permeates 

 them. The wall of these tubular twigs is quite thick, and is 

 alike rough on the exterior and interior faces. The substance 

 within the tubes appears homogeneous, but whether it is solid 

 or fluid could not be determined. The oldest part of the 

 stems is of a reddish-brown colour ; but as they taper ofl" into 

 branchlets they gradually assume a gamboge-colour, and finally 

 terminate in scarcely coloured twigs. 



" Reproduction by fissigemmation (figs. 52—61) is the only 

 method of propagating individuals which I have observed. 

 As a preliminary to this process the monad gradually loses its 

 fusiform shape, and assumes at first an oval contom-, and finally 

 becomes globular (fig. 52). During this transition, both of the 

 prehensile cilia {fl,fl^) become much more conspicuous than 

 usual ; and the body developes a closely fitting hyaline enve- 

 lope (h) about it, thus passing into a sort of encysted state. 

 The contractile vesicle (cv), however, does not seem to cease 

 its pulsations during this period, and moreover it becomes 

 quite conspicuous. This arises mostly from the fact that the 

 body is in a nearly quiet state, and allows the observer to ob- 

 tain a prolonged and undistm-bed view of it. Unfortunately the 

 rate of the pulsations of this organ was not ascertained when 

 the following observations were made, because the whole time 

 was occupied in watching and drawing the various and rapidly 

 changing phases of self-division. 



" After the body assumes a globular shape, as above-men- 

 tioned, both the larger and smaller cilium seem to be under- 

 going a change, and become indistinct in outline. Presently 

 two larger flagella (fig. 53, Jl) burst upon the view, apparently 

 by the longitudinal splitting of the previously single one of 

 the same kind, and rapidly separate from each other by the 

 broadening of the body, leaving between them the smaller 

 cilium. The latter at this time appears much thicker than 

 usual, and seems to be composed of two closely approximated 

 parallel threads (Jl^). By this time the contractile vesicle has 

 also divided into two, which lie closely side by side. 



" At this moment the time noted in one series of observa- 



